FLUID POWERED PERCUSSION TOOL

Description

[0001] The invention concerns a fluid-powered percussion tool for boring, concrete breaking and other demolition work, according to the preamble of claim 1. Such a percussion tool is known from WO 2006/004546 A1. The tool comprises a percussion mechanism, carried devibrated in the tool housing by a swinging joint. The swinging joint is basically identical to the known joint as specified in Swedish patents 528 469 C2 and 528 471 C2 (family member of WO 2006/004546 A1). These also describe how the percussion mechanism is loaded against a neutral position in the tool housing by an elastically resilient element with an integrated line for pressurised fluid. The elastically resilient element in the present invention is substantially more resistant to overloading than the previously known one and furthermore has a longer lifetime. The improved properties are brought about by a new innovative configuration of the elastic element and by a separation and new configuration of the line for pressurised fluid. The invention is suitable for tools where low vibration levels are desired, which in turn lessens the risk of the operator suffering vibration injuries. The fluid normally used is air and the example therefore relates primarily to air-powered tools, even though other fluids such as hydraulic oil can be used.

[0002] The elastically resilient element in the above mentioned patents is configured as a rubber membrane. The membrane is resistant of normally occurring loads and has a mostly acceptable lifetime during normal use of the tool. But the applicant has found by its own testing that the rubber membrane is deficient at handling individual extreme overloads and that relatively short exposure to overloads reduces the lifetime of the element in unacceptable fashion. It is especially difficult to configure the integration of the pressurised fluid connection so that it can handle extreme overloads. Attempts have been made to divide up the pressurised fluid connection among several integrated channels, but the problem remains.

[0003] A helical spring made of steel can be formed with much better lifetime and resistance to overloads. The patent US 2,899,934 describes how to arrange a straight helical spring between the tool housing and the back end of the percussion tool. The percussion tool can only move in linear fashion relative to the housing and is locked into the linear movement by a nonflexible connection for pressurised fluid, with telescopic function. The straight helical spring must have great axial rigidity for sake of its function and at the same time it must allow extreme compression. The latter property can be hard to fulfil, since the spring turns close up and limit the possible compression of the spring. For the percussion tool to have the same freedom of motion as in the aforementioned Swedish patents, a number of technical problems need to be solved:

• The first problem is to arrange a flexible connection for pressurised fluid. In the Swedish patents, the person skilled in the art could get some guidance to integrate the pressurised fluid connection in the elastically resilient element but not to separate the function from the element. Nor is he told how a separated function could be worked out.
• The second problem to be solved is the deficient compressing of the straight helical screw, due to the closed up spring turns.
• The third problem is to arrange the spring to respond with radial suspension to radial loading. If this problem is not solved, the spring will instead have a tendency to slide in its contact surface with the percussion tool or its housing.
• The fourth problem is to design the spring to respond with sufficiently great stiffness to radial suspension.

[0004] The object of the present invention, according to its claims, is to obtain a fluid powered percussion tool which solves the above problem. In the present invention, the problem is solved according to independent claim 1 by introducing and arranging a conical spring in the elastic, resilient element and by introducing and arranging a hose in the flexible connection for pressurised fluid. Preferred embodiments are disclosed in the dependent claims.

[0005] The invention will be described more closely by means of enclosed exemplifying drawings. Figure 1 shows the fluid powered tool, in the form of an air-powered tool, in a lengthways section, seen from the left. Figure 2 shows the fluid powered tool of Fig. 1 in a magnified cross section, seen from the rear.

[0006] Figure 1 shows a fluid-powered percussion tool 1, comprising a housing 2 with a supply channel for pressurised fluid 3, a percussion mechanism 4, a swinging joint 5, an elastically resilient element 6, and a flexible connection for pressurised fluid 7. The flexible connection for pressurised fluid 7 will be described in detail in connection with Fig. 2. The swinging joint 5 is arranged to carry the percussion mechanism 4 relative to the housing 2 at a point situated between the forward end A and the rear end B of the percussion mechanism 4. The function of the swinging joint 5 is described in the previously cited Swedish patents and will therefore not be taken up further in the present application. The elastically resilient element 6 is arranged between the housing 2 and the back part B of the percussion mechanism 4 at a distance from the swinging joint 5. Precisely as in the previously cited Swedish patents, the element 6 is arranged to load the percussion mechanism 4 against a neutral position in the housing 2 and to absorb the vibrational movements of the percussion mechanism 4 during the operation of the tool 1.

[0007] The aforesaid problem with closed-up spring turns upon compression is solved in that the elastically resilient element 6 comprises a conical spring 8. The conical spring 8 is of helical type and in this example is arranged with the smaller end against the percussion mechanism 4 and the bigger end against the housing 2. The spring could also be arranged to have the smaller end against the housing. The smaller end of the conical spring 8 is tantamount to the end having the smallest diameter for the spring turn at the end of the spring and the opposite holds for the bigger spring end. Compared to the straight helical springs known in this context, the parameters of the conical spring 8 can be adapted to much greater extent in order to achieve the necessary compression ability. The parameters of the conical spring 8 are adapted so that the spring turns cannot collide and the spring 8 can be compressed in the axial direction to 20% or less of its free length. However, the axial movement is limited to 18% compression of a bulbous rubber stop 9 which in this example is arranged at the back end of the percussion mechanism 4.

[0008] The problem of sliding during radial suspension is solved by the percussion mechanism 4 and housing 2 having the spring seat 10 adapted to the conical spring's abutment and to secure its abutting part in the radial direction. The spring seat 10 in the percussion mechanism 4 is arranged in the back end of the percussion mechanism 4 and is adapted to the smaller end of the conical spring 8. This spring seat will be described together with Fig. 2. The spring seat 10 in the housing 2 is shaped like a thin circular disk with an inner circular recess that just holds the spring turn at the bigger end of the conical spring 8. The fit between spring turn and inner recess is such that the spring turn can be pressed into the recess by hand. The disk is plastic and mounted by press fit in a recess in the housing 2. It is important for the abutment between conical spring 8 and spring seat 10 to be free of play in the radial direction. The abutment and the radial fixation are furthermore assured in that the conical spring 8 is mounted with prestressing. The conical spring 8 and the distance between the spring seats 10 is adapted so that the conical spring 8 is subjected to an installed compression of 71% of its free length. But a good operation can be achieved already with a compression of 80% or less.

[0009] The introduction of the conical spring 8 has also helped solve the problem of obtaining sufficient stiffness during radial suspension. It turns out that a spring arranged according to the invention should have 1 to 3 times greater stiffness in radial suspension than in axial suspension. As compared to a straight helical spring, the choice of the conical spring 8 provides more opportunities for achieving these properties. The conical spring 8 in the present invention is adapted to have 1.9 times greater stiffness in radial suspension than in axial suspension.

[0010] The radial suspension is limited after a predetermined length by an end stop 12, surrounding the percussion mechanism 4. The end stop 12 also limits the possible axial movement of the percussion mechanism 4 relative to the housing 2 after a predetermined length.

[0011] Figure 2 shows the housing 2, the supply channel for pressurised fluid 3, the flexible connection for pressurised fluid 7 and the back end B of the percussion mechanism 4 with spring seat 10 for the smaller end of the conical spring 8. The conical spring 8 is not shown in Fig. 2. The spring seat 10 is fashioned as a circular groove with U-shaped cross section. The bottom of the U has a diameter slightly greater than the wire diameter of the conical spring 8. To avoid loose play, the inner diameter of the circular groove is somewhat greater than that of the conical spring's 8 turn at the smaller end. The fit between spring turn and groove is adapted so the spring turn can be manually pressed into the spring seat 10.

[0012] The flexible connection for pressurised fluid 7 comprises a hose 11 The hose 11 is made of PVC plastic and reinforced with polyester. The hose 11 comes in meter lengths from the supplier and is cut to suitable length prior to assembly. Uninstalled, in the free state, the hose 11 thus has a basically straight shape. When installed, the hose 11 is curved in an arc so that it fits entirely in the housing 2. When shaping the hose 11 it is important to make sure the radius of the arc meets the specified minimum radius. The cross section in Fig. 2 is just behind the percussion mechanism 4 and at right angles to the lengthways dimension of the mechanism. (The lengthways direction of the percussion mechanism 4 is equal to the dashed centre line through the cylinder of the percussion mechanism 4 in Fig. 1.) Thus, the details shown in Fig. 2 can be said to be projected onto a plane normal to the lengthways dimension of the percussion mechanism 4. Figure 2 shows how normals to the cross section plane through the hose's 11 inlet and outlet form 65-degree angles V when projected in the plane normal to the lengthways dimension of the percussion mechanism 4. This makes the connection for pressurised fluid 7 behave in flexible manner as the percussion mechanism 4 is vibrating and at the same time the hose 11 has adequate lifetime for fatigue. It is also possible to decrease angle V even more so that its normals form a parallel relationship and still achieve an acceptable arrangement. It is also possible to have the hose 11 injection-moulded so it basically retains the curved shape in the free and uninstalled condition. The hose 11 inlet is connected to a nipple connected to the supply channel for pressurised fluid 3, and its outlet to an angled nipple connected to the percussion mechanism 4. The hose 11 is secured to the nipples by hose clips of the 2-lug type.

[0013] The claims of the present application are addressed to a fluid powered percussion tool. The percussion mechanism of the tool can have both percussion and boring configuration by known means and is carried in the tool as described herein. Such a fluid powered percussion and boring tool will therefore come within the scope of the present claims.

[0014] The fluid in its most simple form comprises primarily air. However, other gaseous fluids can be used, as well as liquids like hydraulic oil. The above sample embodiment, however, primarily involves a gaseous fluid like air.

Claims

1. Fluid-powered percussion tool (1) for boring, concrete breaking and other demolition work, comprising a housing (2) with a supply channel for pressurised fluid (3), a percussion mechanism (4), a swinging joint (5) arranged to carry the percussion mechanism (4) relative to the housing (2) at a point situated between the forward end A and the rear end B of the percussion mechanism (4), at least one elastically resilient element (6) arranged between the housing (2) and the percussion mechanism (4) at a distance from the swinging joint (5) and arranged to load the percussion mechanism (4) against a neutral position in the housing (2) and to absorb the vibrational movements of the percussion mechanism (4), and a flexible connection for pressurised fluid (7) for distribution of pressurised fluid from the supply channel for pressurised fluid (3) to the percussion mechanism (4), characterised in that the elastically resilient element (6) comprises a conical spring (8), and in that the flexible connection for pressurised fluid (7) contains a hose (11).

2. Fluid-powered percussion tool (1) according to claim 1, wherein the fluid primarily comprises air.

3. Fluid-powered percussion tool (1) according to claim 1 or 2, wherein the conical spring (8) is arranged with a smaller end against the percussion mechanism (4) and a bigger end against the housing (2).

4. Fluid-powered percussion tool (1) according to any one of the preceding claims, wherein the percussion mechanism (4) and housing (2) comprise the spring seat (10) adapted for the conical spring's (8) abutment and to radially secure its abutting part, and the conical spring (8) is arranged prestressed in the axial direction.

5. Fluid-powered percussion tool (1) according to claim 4, wherein the conical spring (8) and the distance between the spring seats (10) is adapted so that the conical spring (8) is subjected to an installed compression of 80% or less of its free length and the conical spring (8) is adapted to allow compression in the axial direction of 20% or less of its free length.

6. Fluid-powered percussion tool (1) according to any one of the preceding claims, wherein the conical spring (8) has 1 to 3 times greater stiffness in radial suspension than in axial suspension.

7. Fluid-powered percussion tool (1) according to any one of the preceding claims, wherein the hose (11) is arranged in an arc so that the projections of the normals into the cross section plane through the hose's inlet and outlet are parallel or form an angle (V) when projected in a plane normal to the lengthways dimension of the percussion mechanism (4).

8. Fluid-powered percussion tool (1) according to any one of the preceding claims, wherein the hose (11) has a basically straight shape in the uninstalled free state.

9. Fluid-powered percussion tool (1) according to any one of claims 1 to 7, wherein the hose (11) is injection moulded and basically retains the curved shape in the uninstalled free state.

Ansprüche

1. Fluidgepulvertes Schlagwerkzeug (1) zu dem Bohren, Brechen von Beton und sonstige Abbrucharbeit, umfassend ein Gehäuse (2) mit einem Versorgungskanal für Druckfluid (3), einen Schlagmechanismus (4), ein Schwunggelenk (5), das angeordnet ist, den Schlagmechanismus (4) in Bezug zu dem Gehäuse (2) an einem Punkt zu tragen, der zwischen dem vorderen Ende A und dem hinteren Ende B des Schlagmechanismus (4) angesiedelt ist, zumindest ein elastisch federndes Element (6), das zwischen dem Gehäuse (2) und dem Schlagmechanismus (4) in einer Entfernung von dem Schwunggelenk (5) angeordnet ist und angeordnet ist, den Schlagmechanismus (4) gegen eine neutrale Position in dem Gehäuse (2) zu laden und die Vibrationsbewegungen des Schlagmechanismus (4) aufzunehmen, und eine flexible Verbindung für Druckfluid (7) zu der Abgabe von Druckfluid aus dem Versorgungskanal für Druckfluid (3) an den Schlagmechanismus (4), dadurch gekennzeichnet, dass das elastisch federnde Element (6) eine Kegelfeder (8) umfasst und dass die flexible Verbindung für Druckfluid (7) einen Schlauch (11) enthält.

2. Fluidgepulvertes Schlagwerkzeug (1) nach Anspruch 1, wobei das Fluid hauptsächlich Luft umfasst.

3. Fluidgepulvertes Schlagwerkzeug (1) nach Anspruch 1 oder 2, wobei die Kegelfeder (8) mit einem kleineren Ende gegen den Schlagmechanismus (4) und einem größeren Ende gegen das Gehäuse (2) angeordnet ist.

4. Fluidgepulvertes Schlagwerkzeug (1) nach einem der vorstehenden Ansprüche, wobei der Schlagmechanismus (4) und das Gehäuse (2) den Federteller (10) umfassen, die für das Widerlager der Kegelfeder (8) und dazu angepasst ist, seinen Anstoßteil radial zu sichern, und die Kegelfeder (8) in der axialen Richtung vorgespannt angeordnet ist.

5. Fluidgepulvertes Schlagwerkzeug (1) nach Anspruch 4, wobei die Kegelfeder (8) und die Entfernung zwischen den Federtellern (10) so angepasst ist, dass die Kegelfeder (8) einer eingebauten Kompression von 80 % oder weniger ihrer freien Länge unterworfen ist, und die Kegelfeder (8) angepasst ist, eine Kompression in der axialen Richtung von 20 % oder weniger ihrer freien Länge zuzulassen.

6. Fluidgepulvertes Schlagwerkzeug (1) nach einem der vorstehenden Ansprüche, wobei die Kegelfeder (8) in radialer Aufhängung 1- bis 3-mal größere Steifigkeit aufweist als in axialer Aufhängung.

7. Fluidgepulvertes Schlagwerkzeug (1) nach einem der vorstehenden Ansprüche, wobei der Schlauch (11) in einem Bogen angeordnet ist, sodass die Auskragungen der Normalen in die Querschnittsebene durch den Einlass und Auslass des Schlauchs parallel verlaufen oder einen Winkel (V) bilden, wenn sie in einer Ebene normal zu der Längsausdehnung des Schlagmechanismus (4) auskragen.

8. Fluidgepulvertes Schlagwerkzeug (1) nach einem der vorstehenden Ansprüche, wobei der Schlauch (11) in dem nicht eingebauten freien Zustand eine in dem Prinzip gerade Form aufweist.

9. Fluidgepulvertes Schlagwerkzeug (1) nach einem der Ansprüche 1 bis 7, wobei der Schlauch (11) in Spritztechnik verarbeitet ist und in dem nicht eingebauten freien Zustand in dem Prinzip die gekrümmte Form beibehält.

Revendications

1. Outil de percussion (1) mû par un fluide pour le forage, la rupture de béton et d'autres travaux de démolition, comprenant, comprenant un boîtier (2) avec un canal d'alimentation pour un fluide sous pression (3), un mécanisme de percussion (4), un joint pivotant (5) agencé pour acheminer le mécanisme de percussion (4) par rapport au boîtier (2) en un point situé entre l'extrémité avant A et l'extrémité arrière B du mécanisme de percussion (4), au moins un élément élastique (6) agencé entre le boîtier (2) et le mécanisme de percussion (4) à une distance du joint pivotant (5) et agencé pour charger le mécanisme de percussion (4) contre une position neutre du boîtier (2) et agencé pour absorber les mouvements vibratoires du mécanisme de percussion (4), et une liaison souple pour du fluide sous pression (7) pour la distribution du fluide sous pression depuis le canal d'alimentation pour le fluide sous pression (3) au mécanisme de percussion (4), caractérisé en ce que l'élément élastique (6) comprend un ressort conique (8) et la liaison souple pour le fluide sous pression (7) contient un tuyau souple (11).

2. Outil de percussion (1) mû par un fluide selon la revendication 1, dans lequel le fluide comprend principalement de l'air.

3. Outil de percussion (1) mû par un fluide selon la revendication 1 ou 2, dans lequel le ressort conique (8) est agencé avec une extrémité plus petite contre le mécanisme de percussion (4) et une extrémité plus grande contre le boîtier (2).

4. Outil de percussion (1) mû par un fluide selon l'une quelconque des revendications précédentes, dans lequel le mécanisme de percussion (4) et le boîtier (2) comprennent le siège (10) du ressort adapté pour l'aboutement du ressort conique (8) et pour fixer radialement sa partie d'aboutement, et le ressort conique (8) est agencé sous précontrainte dans la direction axiale.

5. Outil de percussion (1) mû par un fluide selon la revendication 4, dans lequel le ressort conique (8) et la distance entre les sièges de ressort (10) sont adaptés de sorte que le ressort conique (8) soit soumis à une compression à l'état installé de 80 % ou moins de sa longueur libre et le ressort conique (8) est adapté pour permettre une compression dans la direction axiale de 20 % ou moins de sa longueur libre.

6. Outil de percussion (1) mû par un fluide selon l'une quelconque des revendications précédentes, dans lequel le ressort conique (8) a une rigidité 1 à 3 fois plus grande dans la direction radiale que dans la direction axiale.

7. Outil de percussion (1) mû par un fluide selon l'une quelconque des revendications précédentes, dans lequel le tuyau souple (11) est agencé dans un arc de sorte que les projections des normales dans le plan en section transversale à travers l'entrée et la sortie du tuyau souple soient parallèles ou forment un angle (V) lorsqu'elles sont projetées dans un plan normal à la dimension longitudinale du mécanisme de percussion (4).

8. Outil de percussion (1) mû par un fluide selon l'une quelconque des revendications précédentes, dans lequel le tuyau souple (11) a une forme fondamentalement droite à l'état libre non installé.

9. Outil de percussion (1) mû par un fluide selon l'une quelconque des revendications 1 à 7, dans lequel le tuyau souple (11) est moulé par injection et conserve fondamentalement la forme incurvée à l'état libre non installé.

Drawing